A single head capstan winch of the kind as herein referred is disclosed in German Offenlegungschrift No. 29 39 993. The capstan head of this known winch is provided with a drum having a relatively smooth surface for a frictional contact with multiple power-transmitting windings of a cable or rope whereby when the capstan head is being driven for hauling-in a load a forward portion of the cable or rope is continuously guided over a larger-sized diameter portion of its drum while a rearward portion of the cable or rope then free of any load runs off at the same time from a smaller-sized diameter portion of the drum. For obtaining the power-transmission with the multiple windings of the cable or rope there is further provided a clamping disk as arranged in parallel to the driving axis of the capstan head which clamping disk is arranged for being coupled to a driving shaft of the capstan head through ratchet means so that in the driven rotational direction of the capstan head a clamping groove is being formed between the axially biased clamping disk and the drum of the capstan head for continuously clamping the cable or rope at its rearward portion before the same free of any load runs off from the capstan head.
In British Pat. No. 1 035 652 a multiple head capstan winch is disclosed that comprises a capstan head which is adapted for being driven by a prime mover in the same manner as the capstan head of such single head capstan winches. Instead of a clamping disk arrangement this kind of multiple head capstan winches has further at least one deflection roller that is arranged in parallel to the capstan head for providing a load-transmitting frictional contact again of a multiplicity of windings of a cable or rope with the drum of the capstan head whereby the two ends of the cable or rope are at the same time fixedly anchored. There are further provided for this winch pressing rollers as also biased by springs which when the capstan head is being driven apply a pressing force each on a single winding of the cable or rope for its guiding on the drum of the capstan head and on the at least singular deflection roller. Such multiple head capstan winches usually allow a much higher power or load transmission in comparison with the single head capstan winches due to the fact that by means of their at least singular deflection roller an improved holding of the cable or rope on the capstan head is being obtained.
This invention accordingly deals with the object of providing a single head capstan winch of the general kind as above referred which without the need of a comparable clamping disk arrangement provides a load-controlled clamping force for the cable or rope to thereby obtain with a comparable driving power for the capstan head at the same time a factor of safety for the holding of a load that at least corresponds to the safety factor of multiple head capstan winches under comparable conditions.